include/net/scm.h

   1 #ifndef __LINUX_NET_SCM_H
   2 #define __LINUX_NET_SCM_H
   3
   4 #include <linux/limits.h>
   5 #include <linux/net.h>
   6 #include <linux/security.h>
   7 #include <linux/pid.h>
   8 #include <linux/nsproxy.h>
   9
  10 /* Well, we should have at least one descriptor open
  11  * to accept passed FDs 8)
  12  */
  13 #define SCM_MAX_FD      253
  14
  15 struct scm_creds {
  16         u32     pid;
  17         kuid_t  uid;
  18         kgid_t  gid;
  19 };
  20
  21 struct scm_fp_list {
  22         short                   count;
  23         short                   max;
  24         struct file             *fp[SCM_MAX_FD];
  25 };
  26
  27 struct scm_cookie {
  28         struct pid              *pid;           /* Skb credentials */
  29         const struct cred       *cred;
  30         struct scm_fp_list      *fp;            /* Passed files         */
  31         struct scm_creds        creds;          /* Skb credentials      */
  32 #ifdef CONFIG_SECURITY_NETWORK
  33         u32                     secid;          /* Passed security ID   */
  34 #endif
  35 };
  36
  37 extern void scm_detach_fds(struct msghdr *msg, struct scm_cookie *scm);
  38 extern void scm_detach_fds_compat(struct msghdr *msg, struct scm_cookie *scm);
  39 extern int __scm_send(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm);
  40 extern void __scm_destroy(struct scm_cookie *scm);
  41 extern struct scm_fp_list * scm_fp_dup(struct scm_fp_list *fpl);
  42
  43 #ifdef CONFIG_SECURITY_NETWORK
  44 static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
  45 {
  46         security_socket_getpeersec_dgram(sock, NULL, &scm->secid);
  47 }
  48 #else
  49 static __inline__ void unix_get_peersec_dgram(struct socket *sock, struct scm_cookie *scm)
  50 { }
  51 #endif /* CONFIG_SECURITY_NETWORK */
  52
  53 static __inline__ void scm_set_cred(struct scm_cookie *scm,
  54                                     struct pid *pid, const struct cred *cred)
  55 {
  56         scm->pid  = get_pid(pid);
  57         scm->cred = cred ? get_cred(cred) : NULL;
  58         scm->creds.pid = pid_vnr(pid);
  59         scm->creds.uid = cred ? cred->euid : INVALID_UID;
  60         scm->creds.gid = cred ? cred->egid : INVALID_GID;
  61 }
  62
  63 static __inline__ void scm_destroy_cred(struct scm_cookie *scm)
  64 {
  65         put_pid(scm->pid);
  66         scm->pid  = NULL;
  67
  68         if (scm->cred)
  69                 put_cred(scm->cred);
  70         scm->cred = NULL;
  71 }
  72
  73 static __inline__ void scm_destroy(struct scm_cookie *scm)
  74 {
  75         scm_destroy_cred(scm);
  76         if (scm->fp)
  77                 __scm_destroy(scm);
  78 }
  79
  80 static __inline__ int scm_send(struct socket *sock, struct msghdr *msg,
  81                                struct scm_cookie *scm, bool forcecreds)
  82 {
  83         memset(scm, 0, sizeof(*scm));
  84         if (forcecreds)
  85                 scm_set_cred(scm, task_tgid(current), current_cred());
  86         unix_get_peersec_dgram(sock, scm);
  87         if (msg->msg_controllen <= 0)
  88                 return 0;
  89         return __scm_send(sock, msg, scm);
  90 }
  91
  92 #ifdef CONFIG_SECURITY_NETWORK
  93 static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
  94 {
  95         char *secdata;
  96         u32 seclen;
  97         int err;
  98
  99         if (test_bit(SOCK_PASSSEC, &sock->flags)) {
 100                 err = security_secid_to_secctx(scm->secid, &secdata, &seclen);
 101
 102                 if (!err) {
 103                         put_cmsg(msg, SOL_SOCKET, SCM_SECURITY, seclen, secdata);
 104                         security_release_secctx(secdata, seclen);
 105                 }
 106         }
 107 }
 108 #else
 109 static inline void scm_passec(struct socket *sock, struct msghdr *msg, struct scm_cookie *scm)
 110 { }
 111 #endif /* CONFIG_SECURITY_NETWORK */
 112
 113 static __inline__ void scm_recv(struct socket *sock, struct msghdr *msg,
 114                                 struct scm_cookie *scm, int flags)
 115 {
 116         if (!msg->msg_control) {
 117                 if (test_bit(SOCK_PASSCRED, &sock->flags) || scm->fp)
 118                         msg->msg_flags |= MSG_CTRUNC;
 119                 scm_destroy(scm);
 120                 return;
 121         }
 122
 123         if (test_bit(SOCK_PASSCRED, &sock->flags)) {
 124                 struct user_namespace *current_ns = current_user_ns();
 125                 struct ucred ucreds = {
 126                         .pid = scm->creds.pid,
 127                         .uid = from_kuid_munged(current_ns, scm->creds.uid),
 128                         .gid = from_kgid_munged(current_ns, scm->creds.gid),
 129                 };
 130                 put_cmsg(msg, SOL_SOCKET, SCM_CREDENTIALS, sizeof(ucreds), &ucreds);
 131         }
 132
 133         scm_destroy_cred(scm);
 134
 135         scm_passec(sock, msg, scm);
 136
 137         if (!scm->fp)
 138                 return;
 139
 140         scm_detach_fds(msg, scm);
 141 }
 142
 143
 144 #endif /* __LINUX_NET_SCM_H */
 145